Re: [PATCH v9 1/5] ARM: add basic support for Trusted Foundations

[Alex Courbot <acourbot-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

On 10/29/2013 05:12 PM, Kumar Gala wrote:
>
> On Oct 28, 2013, at 7:25 PM, Mark Rutland wrote:
>
>> On Mon, Oct 28, 2013 at 11:31:36PM +0000, Tomasz Figa wrote:
>>> On Monday 28 of October 2013 14:56:49 Olof Johansson wrote:
>>>> On Mon, Oct 28, 2013 at 05:57:04AM -0500, Kumar Gala wrote:
>>>>> On Oct 28, 2013, at 5:28 AM, Alexandre Courbot wrote:
>>>>>> Trusted Foundations is a TrustZone-based secure monitor for ARM that
>>>>>> can be invoked using the same SMC-based API on all supported
>>>>>> platforms. This patch adds initial basic support for Trusted
>>>>>> Foundations using the ARM firmware API. Current features are limited
>>>>>> to the ability to boot secondary processors.
>>>>>>
>>>>>> Note: The API followed by Trusted Foundations does *not* follow the
>>>>>> SMC
>>>>>> calling conventions. It has nothing to do with PSCI neither and is
>>>>>> only
>>>>>> relevant to devices that use Trusted Foundations (like most
>>>>>> Tegra-based
>>>>>> retail devices).
>>>>>>
>>>>>> Signed-off-by: Alexandre Courbot <acourbot-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>>>>>> Reviewed-by: Tomasz Figa <t.figa-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>>>>>> Reviewed-by: Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>>>>>> ---
>>>>>> .../arm/firmware/tl,trusted-foundations.txt        | 20 ++++++
>>>>>> .../devicetree/bindings/vendor-prefixes.txt        |  1 +
>>>>>> arch/arm/Kconfig                                   |  2 +
>>>>>> arch/arm/Makefile                                  |  1 +
>>>>>> arch/arm/firmware/Kconfig                          | 28 ++++++++
>>>>>> arch/arm/firmware/Makefile                         |  1 +
>>>>>> arch/arm/firmware/trusted_foundations.c            | 79
>>>>>> ++++++++++++++++++++++ arch/arm/include/asm/trusted_foundations.h
>>>>>>       | 67 ++++++++++++++++++ 8 files changed, 199 insertions(+)
>>>>>> create mode 100644
>>>>>> Documentation/devicetree/bindings/arm/firmware/tl,trusted-foundatio
>>>>>> ns.txt create mode 100644 arch/arm/firmware/Kconfig
>>>>>> create mode 100644 arch/arm/firmware/Makefile
>>>>>> create mode 100644 arch/arm/firmware/trusted_foundations.c
>>>>>> create mode 100644 arch/arm/include/asm/trusted_foundations.h
>>>>>>
>>>>>> diff --git
>>>>>> a/Documentation/devicetree/bindings/arm/firmware/tl,trusted-foundat
>>>>>> ions.txt
>>>>>> b/Documentation/devicetree/bindings/arm/firmware/tl,trusted-foundat
>>>>>> ions.txt new file mode 100644
>>>>>> index 0000000..2ec75c9
>>>>>> --- /dev/null
>>>>>> +++
>>>>>> b/Documentation/devicetree/bindings/arm/firmware/tl,trusted-foundat
>>>>>> ions.txt @@ -0,0 +1,20 @@
>>>>>> +Trusted Foundations
>>>>>> +-------------------
>>>>>> +
>>>>>> +Boards that use the Trusted Foundations secure monitor can signal
>>>>>> its
>>>>>> +presence by declaring a node compatible with
>>>>>> "tl,trusted-foundations"
>>>>>> +under the /firmware/ node
>>>>>> +
>>>>>> +Required properties:
>>>>>> +- compatible : "tl,trusted-foundations"
>>>>>> +- version-major : major version number of Trusted Foundations
>>>>>> firmware
>>>>>> +- version-minor: minor version number of Trusted Foundations
>>>>>> firmware
>>>>>
>>>>> vendor prefix version.
>>>>
>>>> Are you saying he should use tl,version-major tl,version-minor? For
>>>> bindings that are already vendor-specific we haven't (on ARM) asked for
>>>> vendor prefix on properties. It doesn't mean that we should keep going
>>>> down that route though, so I'm just asking for clarification for my own
>>>> edification. :)
>>>
>>> This is a good question. We should decide what the right thing (TM) is and
>>> write it down. I, on the contrary, was convinced that it's the way Kumar
>>> says.
>>
>> The impression I got was that properties should be prefixed when they're
>> extremely vendor-specific and could clash with a more generic property. I'm not
>> sure that firmware will ever have a generic binding given the variation even in
>> the set of implemented functionality.
>>
>> I would imagine that there are many ways different firmwares might be
>> versioned, and I can't see version-major or version-minor clashing with a
>> generic property we might add later. However prefixing would not be harmful, so
>> I'm not opposed to it if others want that.
>>
>> Another option would be to support a fallback compatible list (e.g.
>> "tl,trusted-foundations-${MAJOR}-${MINOR}", "tl,trusted-foundations"), and get
>> versioning information from there. Given that could be painful to handle I
>> don't want to force it if not required.
>>
>> Thanks,
>> Mark.
>
> I'm of the opinion that making all vendor specific properties vendor prefixed is the easiest rule of thumb and leaves no gray area to have to argue about.

All good points, I will vendor-prefix these properties.

Thanks,
Alex.